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So, in the D5200 thread here, we're kind of worried that this exceptional little toy may have more rolling shutter issues than other cameras.

This should be a measurable thing: if we knew how many ms it takes each camera to read the sensor, we wouldn't have to be looking at all those piles of not-really-comparable youtube tests.
Also, when a new camera comes out, we would just have to measure it: no need to compare the D5200 first against a GH2, then against a D800, then a 5D3, then...

In order to get a half-decent measure of this, I would need to get a very short clip from each camera, shot following these instructions:
* camera on a tripod, well levelled, set at 24p and 1/50s shutter
* a vertical line somewhere in the frame, crossing it completely from top to bottom (it can be a pole, or a corner, or a door, etc; if it is clearly tilted it will distort my measure)
* start recording, do a quick pan left at constant speed, then a quick pan right at constant speed, repeat, reapeat, then stop recording
(that's a total of 3 pans left and 3 pans right, which will help average off the measurement errors)

If you want to know how your camera fares in relation to others, record that, then send me a link to the unedited file to similaar.feedback@gmail.com (or through a PM on dvxuser) and I'll use two consecutive frames to measure top-to-bottom delay in relation to frame-to-frame delay.

Using the left-to-right and right-to-left measures, the camera-is-not-really-level and vertical-line-is-not-really-vertical issues should be averaged out. And averaging several clilps should smooth out any issues related with the pan speed not being constant (in any case, to get a constant speed, do a long pan that goes on for a while, even if it has to be slower, instead of just a quick whip-and-stop; if you can't find two consecutive frames where the skew is the same, then the pan is not good).

I ran the tests with my NEX-5N, and the results are very consistent... and also very different from the measures I got when I was using standard footage and trying to measure this. If the line is not vertical, the left-to-right and the right-to-left measures will be very different. Averaging them out gives a very accurate approximation of the true value, but if you don't do that (and it has to be the same vertical line, with the camera exactly in the same position), the numbers can be very misleading.

My original measure for the NEX-5N was 23.4ms, calculated with some standard footage that happened to have a half-useful pan. Then I ran the tests as described above, 5 times, with the following results: 28.8ms, 29.6ms, 28.9ms, 29.8ms, 29.8ms.

I have the US version, but yes, I was very surprised to see it compare so badly with the BMC at 24p. I never thought of this little toy as particularly shutter-impaired, maybe I've subconsciously adjusted to slow camera movement over the last couple of years, with a T2i first and then with the 5N...

Squig is sending me some files soon, so we'll have a few more cameras to compare.

NEX-5N: 29.4 (exactly the number I had with my tests!)
D5200: 22.4
5D2: 25.9
5D3: 20.5

He also sent me these numbers, which he found somewhere on the net, and which, given our 5D2 result, may be comparable with the list above:
Scarlet 14ms
F65 14ms
FS100 15ms
AF100 14.85ms
C300 16ms
Red One MX 16.6ms
7D 21ms
5D MKII 25ms
GH1 25ms
D90 33ms

look at the vertical line that gets skewed
measure horizontal difference from top point in frame t to bottom point in frame t (A pixels)
measure horizontal difference from top point in frame t to top point in frame t+1 (B pixels)

if B pixels is 1000/24=41.7ms, then A pixels is (41.7*A/B) ms

it is normal that the left pan and the right pan will give you different numbers, but the average should be pretty consistent